This invention relates to new and improved methods and apparatus for forming a necked-in portion and attachment flange on a metallic can body.
In the manufacture of two and three piece can type containers from metallic sheet material such as steel, steel alloys, and aluminum, a can body member of generally cylindrical shape is formed with both ends open (for three piece cans), or with only one end open (for two piece cans). In order to close the open end/s of the can body, portions of the can body adjacent the open end/s are necked down and an attachment flange portion is formed at the end/s of the can body. The attachment flange portion is utilized for sealing association with an end plate member to close the open end/s of the can body to form a can with contents such as beer or soft drinks sealed therewithin.
It has been common commercial practice to first separately perform the necking operation by separate necking apparatus and methods such as disclosed in U.S. Pat. No. 3,687,098 of John Hardy Maytag, issued Aug. 29, 1972, and owned by the assignee of the present invention. Other United States patents relating to necking apparatus and methods include: U.S. Pat. Nos. 3,898,828; 3,831,416; 3,820,486; 3,812,696; 3,808,868; 3,786,957; 3,797,431; 3,771,476; 3,763,807; 3,757,558; 3,690,279; 3,680,350; 3,600,927 and 3,468,153. After completion of the separate necking operation, it has been common commercial practice to then separately perform a flanging operation by separate flanging apparatus and methods as illustrated in U.S. Pat. Nos. 3,548,769 and 3,406,648. While necking and flanging apparatus and methods have been proposed for simultaneous necking and flanging operations, as illustrated by U.S. Pat. Nos. 3,951,083; 3,797,429; 3,782,315; 3,782,314; 3,765,351; 3,757,555; 3,698,337 and 3,688,538, the applicants are unaware of any successful commercial usage of such simultaneous necking and flanging apparatus and methods.
Forming of the attachment flange portion is a critical operation in manufacture of a can having good sealing characteristics. In addition, substantial savings in cost of sheet materials may be effected by reduction of the diameters of the can flange portion and the end plate members. Many present commercially available cans have substantially uniform diameter can body members and end plate members. However, it has been determined that by use of the present invention the attachment flange portion of the can body member may be more easily formed with a diameter enabling the use of an end plate member of smaller diameter than the diameter of the main sidewall portion of the can body member. The satisfactory formation of an attachment flange portion of suitable diameter has been difficult and many problems have been encountered in developing methods and apparatus for relatively high speed reliable defect-free manufacture thereof.
The present invention solves many of those problems by providing a method and apparatus for forming an attachment flange portion by use of rotatable housing means having a rotatable self centering sleeve means for receiving a can body member therewithin; an outer forming means mounted on and rotatable with the rotatable housing means and having an annular curved outer forming surface engageable with the outer peripheral surface of an unformed end portion of the side wall portion of the can body member adjacent the rim portion; the first rotatable inner forming means for location within the can body member having a support surface in supporting engagement with only a portion of the sidewall of the can body member axially inwardly spaced from the curved outer forming surface and a first inner forming surface opposite the area of forming engagement between the curved outer forming surface and the unformed end portion of the can body member; a second rotatable inner forming means for partial location within the can body member having a support surface in supporting engagement with the rim portion of the can body member and a second inner forming surface opposite the area of forming engagement between the curved outer forming surface and the unformed end portion; and adjustment means for permitting axial separation of the first and second inner forming means during the forming operation.